I have a 96' Honda Civic EX and it seems to have battery issues in Winter. If it isn't driven for a day the battery will typically be dead. In worst case scenario I have even driven it at night only for it to be dead by morning. I got a new battery 2 years ago assuming that was the issue but it did not resolve anything. I am looking into what the possible problem is at it nears winter again. Oh and it has never been dead in the summer, it just seems in winter it doesn't do well. I took some readings yesterday and have tried to narrow it down again.

With a DMM here are the following readings I get:
Two readings on battery on two different days. 12.32V and 12.25V
With car running 14.47V
The current draw with car off is 40mA.

According to what I have read those numbers aren't abnormal, and I can't figure out what is causing my battery issues in winter. I read that a range of 20-50mA current draw with car off is about normal, BUT I don't know the specifications of what my specific car should be drawing when off. I do have some stereo equipment in my car so I have thought it could possibly be that.

Its not a big system, just a 300watt amp for my speakers and 250watt amp for my subwoofer. A total of 550 watts, which to me doesn't seem like it should have a huge power drain or hurt on the system (i could be wrong).
Anyways I did some fiddling around and here is what i found. I had a feeling one of my amps is going bad or having issues based on a couple things.
Long story short: If I disconnect one of my amps, the current drops from 40mA to 38mA (not a big deal). But if i disconnect the amp that has given me troubles it drops all the way down to 8-9mA. It drops nearly 32mA just by disconnecting the 'bad' amp.

Assuming the 'bad' amp is causing a parasitic drain I wanted to narrow it down and find out what the issue was. The problem is that the 'On' light on the amp is NOT on when the car is off, which tells me the amp is not receiving power. This doesn't make sense to me because just by disconnecting that amp the current draw of my car when off drops by 32mA. I have a decent understanding on the electrical stuff but still much to learn. Assuming the amp is drawing 32mA when car is off, should it not be receiving power?

At the moment I have that amp disconnected until I can find out what is wrong, it could very well be the amp or something else going on that I can't pinpoint. The way I see it, i have 2 choices: purchase a new amp, or install a relay or switch. The amp has had issues so I don't have a problem purchasing a new one, just worried i install the new one and realize the same issue exists.

Thanks for any advice and tips. I would really like to know if anyone knows how much current a 96 honda civic ex should draw when the car is off. If i have a baseline to compare my readings to it would help a lot. I did not find the information I wanted from the Haynes Repair Manual.

 

You measured less than 10 mA with just the car stock, that seems normal. Even 40 mA is nowhere near enough to drain a good battery in one day. (0.04 A x 24 hr = 0.96 A-hr; a good battery holds at least 20 A-hr).

Maybe the bad amp draws a higher level sometimes, something else is coming on that wasn't on during your test, or the battery itself is faulty, or you have a bad connection or problem with the starter that makes you think the battery is dead when it is not.

I'd disconnect the battery entirely when parked, then see if it starts good when you reconnect it the next day. If it does not, check the battery voltage directly.

 

550W is about 45A draw if you are going full blast on amps, isn't it?
What is typical amp rating on Honda alternator? 50 ~ 60A?

14.45V with engine running,,, Is it with all of electrical load applied? ie, lights and stereos on?

Have you had the battery load tested? Is it a conventional battery? How is the levels on cells? Have you been using distilled water?

I was just wondering,,,,

 

Yea it's odd that it never drains it during the summer. It seems to have the most effect in winter. My thoughts is that while it may only be draining a little bit the battery may never get fully charged. And when its cold it just makes it that much worse. I also have a feeling something else is drawing that does not come on during tests. If it is sporadic, it will be tough to find and fix. I replaced the starter a few years ago, but in winter after sitting for a day or two I will hardly get dome lights or any lights inside the vehicle to come on, leading me to believe it may not be the starter.

 

14.45V is with the engine running but without lights or stereo, I suppose that should be the next test. I have not had the battery load tested, it is a conventional battery-a Duralast Gold battery. I checked the cells and the water level is still to the top I have never had to fill them. I bought a new battery 2 years ago assuming my issues were from the battery, but continue to have the issues.

I have thought about buying an Optima yellowtop, but again I have no idea if that will help and prevent dead battery in winter. I have seen some products where I could hook my car up every night to some sort of battery charger module. Ideally I would like to get to the root of the problem, if that isn't possible I will find the next best thing to get my car through the winter.

I have also been reading up on something called The Big 3 upgrade. It would consist of upgrading wire from battery positive to alternator, engine block to chassis ground, and battery ground to chassis ground. The idea is that stereo systems draw much more power and while the alternator may be able to keep the battery charger, the stock small gauge wire on those 3 locations is preventing/hindering the alternator and charging abilities.


I should test the voltage with all accessories running and car stereo at my normal listening levels and look for any drops or charging issues. I have not done this yet so I don't p*ss off the neighbors.

 

The reading of 14.5 volts with car running is proper, proves that it is going to fully charge. At idle the alternator may normally not keep up with lights and stereo, so if you do that test rev the engine up to simulate cruise rpm. You can also connect a voltmeter inside the car (to the cigarette lighter for a temporary check) and monitor voltage while driving. Really though if the battery weren't being charged, it wouldn't start the car 5 minutes after you park-- it wouldn't be a difference between that and sitting overnight. So I really suggest you just disconnect the battery during the night to tell if something in the car is draining it or it just goes dead by itself.

 

Alright will do, it doesn't seem to have issues till it gets real cold out. I expect in the next few weeks here in Wisconsin. At the time I have the bad amp disconnected to see if I can tell a difference. I don't think it has ever been dead on me in fall, but has struggled to start as if the battery is weak. I will be checking the battery regularly and disconnecting the battery over night to narrow it down though.

Edit: I should add that yesterday I took the battery out of the car and put it on a trickle charge for about 6 hours, ending at 8pm, at 9am this morning I checked the voltage and it read at ~12.7V if i remember correctly. I don't know if that's enough evidence that the battery is good and holds a charge. It did sit for about 13 hours not connected to anything after being fully charged and checked out OK this morning.

As a side note, I always get little sparks when I reattach the ground to negative terminal on battery. My brother has a honda civic very similar to mine and his has no sparks. Just find it odd, I will read up on it though. After disconnecting the bad amp I get less sparks/smaller sparks but they are still visible and I can hear it spark. Normal?

 

Amps have capacitors inside across the "unswitched" power straight from the battery. The sparks are normal as the capacitors take a surge to charge up when first connected.

 

I was doing some reading on lead acid battery. For 12V automotive battery, there is a voltage you want avoid, called "gassing voltage" which limits how high the voltage can go before undesirable chemical reactions take place. That voltage is 14.4V, as I found out.

The typical charging voltage is between 2.15 volts per cell (12.9 volts for a 6 cell battery) and 2.35 volts per cell (14.1 volts for a 6 cell battery). These voltages are appropriate to apply to a fully charged battery without damage.

Provided your voltmeter is accurate, the charging voltage of 14.47V may be too much. ??

Open circuit voltage you listed are 12.32V and 12.25V. These are like 50 to 60% of full charge state.

Temperature will affect the performance of battery, too. If your car sits overnight, it will be colder in the morning. Oil in the engine will be thicker, too. The starter motor will have hard time turning and the battery will have hard time supplying needed cranking amps when cold.

And this is my guess,,,